Fluid pumps or motors



@mf f July 27, 1965 R. J. lFn-:LD 3,196,801

FLUID PUMPS OR MOTORS Filed Sept. 25, 1963 United States Patent O3,196,31 EUUED PUMPS GR MGTGRS Richard Joseph lield, Beecrott, New SouthWales, Australia, assigner' to Joseph Lucas (Industries) Limited,`Birmingham, Engiand Filed Sept. 2S, 1963, Ser. No. 311,358 Claimspriority, application Great Britain, ct. 11, 1962, 38,602/62 1 Claim.(Cl. 10S- 162) This invention relates to fluid pumps or motors of thereciprocatory piston type and comprising a hollow body, a cylinderbarrel rotatable within the body, a plurality of angularly spacedlongitudinal bores Within the barrel, a plurality of spherical headedpistons occupying the bores respectively, a rotatable carrier within thebody, means connecting the pistons to the carrier at angularly spacedpoints respectively, and means for varying the angle between the axes ofthe carrier and barrel respectively the arrangement being since that asthe carrier and barrel are rotated reciprocatory movement will beimparted t the pistons.

With such pumps or motors ditiiculty has arisen in providing an elicientseal between the pistons and the bores and the object of this inventionis to minimise this diliiculty in a simple and convenient manner.

According to the invention in a fluid pump or motor of the kind speciiedeach piston is provided with a resilient sealing ring located in agroove in the periphery of the piston, the groove being so positioned inrelation to the spherical centre of the piston that the line of contactof the sealing ring and the wall of the bore lies wholly in front orwholly behind the line of contact of the piston nad the wall of the boreduring the operation of the pump or motor.

in the accompanying drawings- FIGURE 1 is a section View of one exampleof a hydraulic pump embodying the invention and M FGURE 2 is an enlargedView of a part of the pump shown in FGURE l.

Referring to the drawings there is provided a multipart body constitutedby a hollow main body 1 of stepped cylindrical form and a cover 1aclosing the Wider end of the body. Extending into the wider part of thebody is a rotatable shaft 2 which at one end is adapted for connectionto an engine and at its other end is drivingly engaged with a rotarycarrier 3 which is supported in anti-friction bearings 4 in the body.

Within the body is mounted a port-block 5 which has a flat face 6presented towards the carrier and an opposite face 7 of part cylindricalform, whereby the block may be tilted, wlL'ch bears against .acomplementary surface formed on the cover. Moreover rotation of theportblock is prevented by the abutment of cheeks S formed on the coverwith complementary surfaces (not shown) formed on the port-block.

Mounted on the dat face of the port block is a spigot 1@ upon which isrotatably mounted, by means of an anti-friction bearing 12, a rotarycylinder barrel 11. The cylinder barrel is in driving engagement withthe carrier by means of a universally jointed coupling 13 which is heldin position by a thrust-pad 14 loaded by springs 9.

Formed in the cylinder barrel are a plurality of equiangularly -spacedcylinders 15 which are extended to ddgdhl Patented July 27, 1965 formports 16 adjacent the port-block. Within the cylinders are mounted aplurality of pistons 17 respectively which are provided with piston rodsterminating in spherical ends 2S which are engaged in equi-angularlyspaced spherical seatings in the carrier 3.

ln the flat face of the port bloclr are formed an arcuate inlet port 2@and an arcuate outlet port with which thc ends of the cylinders registerin turn as the cylinder barrel rotates. The arcuate inlet and outletports are connected respectively through passages 24 extending throughthe port block to an inlet 22 and outlet 23 -in the cover wherebyhydraulic liquid can be admitted t0 and discharged from the cylinders.

Thus, when the dat face of the port block is inclined relative to theshaft axis and the latter is rotated, the pistons are reciprocated.Hydraulic liquid is thus drawn into the cylinders while they are incommunication with the inlet port and discharged when they are incommunication with the outlet port.

L The parts of the piston 17 which contacts the wall of the cylinder isof spherical form so that line Contact, indicated by the dotted line 27'in FIGURE 2, is always maintained between the piston and the wall. Inorder to provide a liuid seal between the piston and the wall of thebore a peripheral groove 26 is provided on the piston and in the grooveis located a sealing ring 28. The groove is so disposed in relation tothe spherical centre ot the piston that the line of contact of thesealing ring and the wall of the bore lies wholly in front of the lineof contat of the piston and the wall of the bore during the operation ofthe pump.

By a construction of pump as above described the sealing ring isrelieved of loads due to centrifugal force acting on the piston and isthus better able to perform its sealing function. However the wear onthe sealing ring is reduced.

lt will be appreciated that the groove 26 could be formed in the pistonso that the sealing ring lies wholly behind the line of contact 0f thepiston and cylinder during operation of the pump.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

Hydraulic apparatus comprising in combination a hollow body, a cylinderbarrel rotatably mounted within the body, a rotatable carrier mountedwithin the body, means for varying the angle between the axis of thebarrel and carrier respectively, a plurality of longitudinal cylindersformed in the barrel, a plurality of spherical headed pistons occupyingthe cylinders respectively, means connecting the piston to the carrierat angularly spaced points respectively, a plurality of grooves formedin the periphery of the pistons respectively at points removed from thelines of contact of the pistons and the cylinders and a plurality ofresilient sealing rings occupying the grooves respectively.

Reterences Cited by the Examiner UNITED STATES PATENTS 2,792,790 5/57Capps 103-178 2,956,508 l0/ 60 Wahlmark 103-162 2,956,845 10/60 Wahlmark10B-162 LAURENCE V. EFNER, Primary Examiner.

